Sitafloxacin (name according to International Nonproprietary Names (INN)) is a compound having the chemical structure shown below that was granted a patent in Japan (Japanese Patent No. 2714597).
This compound exhibits very high antimicrobial activities and high safety and has been under study with expectation for application as an excellent quinolone synthetic antimicrobial agent.
Sitafloxacin is a promising antimicrobial agent having potent antimicrobial activities, especially in the treatment of serious infectious diseases. Therefore, it is desirable that sitafloxacin is available in a formulation suited to not only orally but also parenterally. The present inventors have researched into preparation of a liquid preparation comprising an aqueous sitafloxacin solution. It has turned out as a result that sitafloxacin in aqueous solution lacks stability to light. Specifically they have revealed that sitafloxacin in aqueous solution undergoes decomposition on being irradiated with light, resulting in reductions of sitafloxacin content, pH, and light transmission. Formation of sitafloxacin related substances was also determined. Namely, it has been revealed that the light stability of an aqueous sitafloxacin solution needs to be improved in order to supply a liquid preparation comprising an aqueous sitafloxacin solution.